Openrefine: XML Parsing Error: not well-formed when canceling an import

[thadguidry]

When canceling an import preview an error is thrown in Firefox Console.

To Reproduce

Steps to reproduce the behavior:

1. Use the Clipboard importer to import some text
2. Click Next and see the preview rows.
3. Click Start Over button and notice the error in Firefox Console
   

Current Results

XML Parsing Error: not well-formed
Location: http://127.0.0.1:3333/command/core/cancel-importing-job?jobID=4
Line Number 1, Column 1:

Expected Behavior

No XML Parsing Error

Screenshots

Versions

• Operating System: Windows 10
• Browser Version: Firefox latest
• JRE or JDK Version: JDK8
• OpenRefine: openrefine-3.4-beta-388-g1dcc832

Datasets

Additional context

[thadguidry]

Also happens for

XML Parsing Error: not well-formed
Location: http://127.0.0.1:3333/command/core/recon-judge-similar-cells?project=2519405186300
Line Number 1, Column 1: recon-judge-similar-cells:1:1

when clicking on the "Match All Identical Cells" button during Reconciling a cell value.

[thadguidry]

And happens when clicking on the Undo blue link on the yellow banner that pops up after you perform an operation:

XML Parsing Error: not well-formed
Location: http://127.0.0.1:3333/command/core/undo-redo?undoID=1595977412132&project=2519405186300
Line Number 1, Column 1: undo-redo:1:1

[thadguidry]

Transpose -> Columnize by Key/Value columns

XML Parsing Error: not well-formed
Location: http://127.0.0.1:3333/command/core/key-value-columnize?keyColumnName=item+-+batters+-+batter&valueColumnName=item+-+type&noteColumnName=item+-+batters+-+batter+-+id&project=2519405186300
Line Number 1, Column 1: key-value-columnize:1:1

[wetneb]

This is just because the HTTP responses from the backend lack a Content-Type: application/json header (many commands return JSON as plain text).