Kibana version:
master / v7.5.0, as of 12/10/2019
Original install method (e.g. download page, yum, from source, etc.):
Started a local Kibana server with _Embeddable Explorer_ enabled via:
yarn start --plugin-path test/plugin_functional/plugins/kbn_tp_embeddable_explorer/
Describe the bug:
When visualizations are added to an embeddable dashboard, an 鈿狅笍 Error in visualisation: Invalid renderer id 'visualization' error toaster appears, and the contents of the widget are not rendered, as shown in the screenshot below:

A different error also occurs when adding a Lens embeddable to a dashboard:

I found and suggested a potential fix the the Lens error above in the _Any additional context_ section of this github issue.
Steps to reproduce:
yarn start --plugin-path test/plugin_functional/plugins/kbn_tp_embeddable_explorer/
EE Embeddable Explorer icon in the Kibana sidebar, to navigate to the Embeddable Explorer sample app Dashboard Container tab to view the Dashboard Container exampleAdd panel from the popup menuTypes dropdown and select Visualization to filter the Add panels viewError in visualisation: Invalid renderer id 'visualization' error toaster appears, and the contents of the widget are not rendered. Clicking on the See the full error button in the toaster reveals the following:Error: invalid renderer id 'visualization'
at _callee$ (webpack-internal:///./src/plugins/expressions/public/render.ts:106:72)
at tryCatch (webpack://%5Bname%5D/./node_modules/regenerator-runtime/runtime.js?:45:40)
at Generator.invoke [as _invoke] (webpack://%5Bname%5D/./node_modules/regenerator-runtime/runtime.js?:271:22)
at Generator.prototype.<computed> [as next] (webpack://%5Bname%5D/./node_modules/regenerator-runtime/runtime.js?:97:21)
at asyncGeneratorStep (webpack-internal:///./src/plugins/expressions/public/render.ts:25:103)
at _next (webpack-internal:///./src/plugins/expressions/public/render.ts:27:194)
at eval (webpack-internal:///./src/plugins/expressions/public/render.ts:27:364)
at new Promise (<anonymous>)
at ExpressionRenderHandler.eval (webpack-internal:///./src/plugins/expressions/public/render.ts:27:97)
at ExpressionRenderHandler.eval [as render] (webpack-internal:///./src/plugins/expressions/public/render.ts:131:20)
Errors in browser console (if relevant):
The following errors also appear in the developer console. They appear to refer to saved object IDs that are referenced in the example code, but don't exist in a default Kibana installation:
18:04:55.272 webpack-internal:///./src/legacy/core_plugins/kibana/public/visualize/embeddable/visualize_embeddable_factory.tsx:250 Error: Could not locate that visualization (id: 3fe22200-3dcb-11e8-8660-4d65aa086b3c)
at SavedObject.applyESResp (webpack-internal:///./src/legacy/ui/public/saved_objects/saved_object.js:263)
at processQueue (webpack://%5Bname%5D/./node_modules/angular/angular.js?:17948)
at eval (webpack://%5Bname%5D/./node_modules/angular/angular.js?:17996)
at Scope.$digest (webpack://%5Bname%5D/./node_modules/angular/angular.js?:19115)
at eval (webpack://%5Bname%5D/./node_modules/angular/angular.js?:19435)
at TaskTracker.completeTask (webpack://%5Bname%5D/./node_modules/angular/angular.js?:21234)
at eval (webpack://%5Bname%5D/./node_modules/angular/angular.js?:6814)
_callee3$ @ webpack-internal:///./src/legacy/core_plugins/kibana/public/visualize/embeddable/visualize_embeddable_factory.tsx:250
18:04:55.272 webpack-internal:///./src/legacy/core_plugins/kibana/public/visualize/embeddable/visualize_embeddable_factory.tsx:250 Error: Could not locate that visualization (id: 4c0f47e0-3dcd-11e8-8660-4d65aa086b3c)
at SavedObject.applyESResp (webpack-internal:///./src/legacy/ui/public/saved_objects/saved_object.js:263)
at processQueue (webpack://%5Bname%5D/./node_modules/angular/angular.js?:17948)
at eval (webpack://%5Bname%5D/./node_modules/angular/angular.js?:17996)
at Scope.$digest (webpack://%5Bname%5D/./node_modules/angular/angular.js?:19115)
at eval (webpack://%5Bname%5D/./node_modules/angular/angular.js?:19435)
at TaskTracker.completeTask (webpack://%5Bname%5D/./node_modules/angular/angular.js?:21234)
at eval (webpack://%5Bname%5D/./node_modules/angular/angular.js?:6814)
_callee3$ @ webpack-internal:///./src/legacy/core_plugins/kibana/public/visualize/embeddable/visualize_embeddable_factory.tsx:250
18:04:55.272 webpack-internal:///./src/legacy/core_plugins/kibana/public/discover/embeddable/search_embeddable_factory.ts:144 Error: Could not locate that search (id: be5accf0-3dca-11e8-8660-4d65aa086b3c)
at SavedObject.applyESResp (webpack-internal:///./src/legacy/ui/public/saved_objects/saved_object.js:263)
at processQueue (webpack://%5Bname%5D/./node_modules/angular/angular.js?:17948)
at eval (webpack://%5Bname%5D/./node_modules/angular/angular.js?:17996)
at Scope.$digest (webpack://%5Bname%5D/./node_modules/angular/angular.js?:19115)
at eval (webpack://%5Bname%5D/./node_modules/angular/angular.js?:19435)
at TaskTracker.completeTask (webpack://%5Bname%5D/./node_modules/angular/angular.js?:21234)
at eval (webpack://%5Bname%5D/./node_modules/angular/angular.js?:6814)
_callee$ @ webpack-internal:///./src/legacy/core_plugins/kibana/public/discover/embeddable/search_embeddable_factory.ts:144
Since the above saved object IDs (referenced in dashboard_input.ts) don't exist locally, only the "Hello World" and "Contact Card" widgets are successfully rendered by default in my local development environment.
Any additional context:
I also observed a separate issue, where after adding a Lens visualization to the dashboard, the widget was rendered with a [lens_merge_tables] > Function esaggs could not be found. error, per the screenshot below:

I was able to resolve the error above by adding the following import to dashboard_container_example.tsx:
import { npSetup } from 'ui/new_platform';
...and then invoking the registerFunction(esaggs) via the following:
npSetup.plugins.expressions.registerFunction(esaggs); // fix esaggs error
After making the change above, Embeddable Explorer successfully renders a Lens visualization added to the dashboard, as shown in the screenshot below:
Please consider updating dashboard_container_example.tsx to include the above fix, to enable rendering Lens visualizations in a dashboard.

cc @stacey-gammon
Pinging @elastic/kibana-app-arch (Team:AppArch)
Thanks @andrew-goldstein ! cc @streamich. I suspect the tests are broken too (turned off due to https://github.com/elastic/kibana/issues/43087) . Will investigate tomorrow.
Actually, this is an issue with the visualize embeddable specifically so the team is Kibana App, not App Arch. But I can still try to help tomorrow if no one else jumps on it, since you are hoping to have this fixed by 7.6 to embed visualizations.
My guess is this broke it: https://github.com/elastic/kibana/pull/50294
and that we probably need a hacks entry in uiExports that points to the boots file so the esaggs function is always registered.
will see if I can test this theory out soon
Oh wait no, I bet each legacy app that wants to use legacy visualize embeddables needs to have import 'uiExports/interpreter'; somewhere
Yep, that fixes it.

Fixed with https://github.com/elastic/kibana/pull/52945
Most helpful comment
Oh wait no, I bet each legacy app that wants to use legacy visualize embeddables needs to have
import 'uiExports/interpreter';somewhere