Typedoc: AssertionError [ERR_ASSERTION]: Missing parent symbol when converting function

[doberkofler]

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ERR_ASSERTION

Expected Behavior

No exception in TypeDoc 0.20.2 but error in TypeDoc 0.20.3 and TypeDoc 0.20.4

Actual Behavior

npx typedoc
TypeDoc exiting with unexpected error:
AssertionError [ERR_ASSERTION]: Missing parent symbol when converting function
    at Object.convertFunctionOrMethod (/Users/doberkofler/MyDev/ljs_app/trunk/periscope/node_modules/typedoc/dist/lib/converter/symbols.js:134:5)
    at Object.convertSymbol (/Users/doberkofler/MyDev/ljs_app/trunk/periscope/node_modules/typedoc/dist/lib/converter/symbols.js:75:79)
    at Converter.convertExports (/Users/doberkofler/MyDev/ljs_app/trunk/periscope/node_modules/typedoc/dist/lib/converter/converter.js:167:23)
    at Converter.compile (/Users/doberkofler/MyDev/ljs_app/trunk/periscope/node_modules/typedoc/dist/lib/converter/converter.js:143:34)
    at Converter.convert (/Users/doberkofler/MyDev/ljs_app/trunk/periscope/node_modules/typedoc/dist/lib/converter/converter.js:42:14)
    at Application.convert (/Users/doberkofler/MyDev/ljs_app/trunk/periscope/node_modules/typedoc/dist/lib/application.js:151:31)
    at run (/Users/doberkofler/MyDev/ljs_app/trunk/periscope/node_modules/typedoc/bin/typedoc:59:25)
    at Object.<anonymous> (/Users/doberkofler/MyDev/ljs_app/trunk/periscope/node_modules/typedoc/bin/typedoc:26:1)
    at Module._compile (internal/modules/cjs/loader.js:1063:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1092:10) {
  generatedMessage: false,
  code: 'ERR_ASSERTION',
  actual: undefined,
  expected: true,
  operator: '=='
}

Steps to reproduce the bug

typedoc.json

{
    "entryPoints": [
        "./src/components",
        "./src/data",
        "./src/framework"
    ],
    "out": "doc",
    "exclude": [
        "**/*.js"
    ],
    "excludeExternals": true,
    "hideGenerator": true
}

Environment

• Typedoc version: 0.20.4
• TypeScript version: 4.1.3
• Node.js version: 14.15.3
• OS: macOS 11.1

[BobKerns]

I hit the same problem about simultaneously. In my case, I tracked it down to the following module declaration:

declare module 'present';
declare function present(): number;

This was needed because of missing declarations for this:

import present from 'present';

My workaround: exclude the file present.d.ts in my typedoc.json file.

Alternate workaround:

const present = require('present') as () => number;

(and comment out the present.d.ts file; the problem seems to stem from processing the declaration, rather than the usage.)

[BobKerns]

The error message is completely opaque. To track down what symbol was the cause, I changed the assert in typedoc/dist/lib/converter/symbol.js to be this:

    const showScope = s => JSON.stringify({id: s.id, name: s.name, originalName: s.originalName, kind: s.kind})
    assert(parentSymbol, !parentSymbol && `Missing parent symbol when converting function ${symbol.escapedName} scope ${showScope(context.scope)} parent ${showScope(context.scope.parent)}`);

The !parent symbol && is to avoid creating the string on every assert call, as I expect that's rather frequent. This isn't the optimum solution to the opacity, but it was enough for me to find a solution.

[doberkofler]

@BobKerns Thank you for the debugging tip (I was just too lazy to dig into the source and hoped for some feedback)

I just added the code change and am getting the following error

AssertionError [ERR_ASSERTION]: Missing parent symbol when converting function isStyleSupported scope {"id":7105,"name":"framework/browser/featureDetection","originalName":"framework/browser/featureDetection","kind":1} parent {"id":0,"name":"","originalName":"","kind":0}

without obvious reason (to me) in the following code

function isStyleSupported(prop: string, value: string = 'inherit'): boolean {
    const el = window.document.createElement('div');
    const camelRe = /-([a-z]|[0-9])/ig;

    // Try the native standard method first
    if ('CSS' in window && 'supports' in window.CSS) {
        return window.CSS.supports(prop, value);
    }

    // Check Opera's native method
    if ('supportsCSS' in window) {
        return (window as any).supportsCSS(prop, value); // eslint-disable-line @typescript-eslint/no-explicit-any
    }

    // Convert to camel-case for DOM interactions
    const camel = prop.replace(camelRe, function (all, letter) {
        return String(letter).toUpperCase();
    });

    // Check if the property is supported
    const support = camel in el.style;

    // Assign the property and value to invoke the CSS interpreter
    el.style.cssText = prop + ':' + value;

    // Ensure both the property and value are supported and return
    return support && (el.style as any)[camel] !== ''; // eslint-disable-line @typescript-eslint/no-explicit-any
}

$(function () {
    if (!isStyleSupported('display', 'flex')) {
        $('body').addClass('no-flexbox');
    }

    if (!isStyleSupported('animation-name')) {
        $('body').addClass('no-css-animation');
    }
});

[BobKerns]

It's not obvious to me either. I didn't attempt to understand what was going wrong. Once I identified the function and context I proceeded by trial and error, removing stuff. That was pretty limited in my case; it may be more challenging here.

If you want to try to debug it, ndb may be helpful.

https://github.com/GoogleChromeLabs/ndb

[Gerrit0]

This is caused by the function being present in a non-module file, the assertion that we have a parent isn't appropriate there - it should only be asserted if the function being converted is a method. Fixed in 0.20.5