[4.0] Extension update check

[brianteeman]

Steps to reproduce the issue

With current J4 the extension update check never completes. Looking at the console is the following error

 Uncaught SyntaxError: Unexpected token < in JSON at position 0
    at JSON.parse (<anonymous>)
    at onSuccess (extensionupdatecheck.js?61f0bd7f3a1e51d20f4535590f3e4657:28)
    at XMLHttpRequest.o.onreadystatechange (core.min.js?61f0bd7f3a1e51d20f4535590f3e4657:1) 

@dgt41

[C-Lodder]

@brianteeman - could you replace the minified code with the uncompressed code and try again, to get the exact line number?

[dgrammatiko]

@C-Lodder its not the javascript, the error comes from php, the returned data is not JSON formatted. Something throws an error and the return data is html formatted

[dgrammatiko]

@brianteeman check #17846

[joomla-cms-bot]

Set to "closed" on behalf of @franz-wohlkoenig by The JTracker Application at issues.joomla.org/joomla-cms/17844

[ghost]

closed as having Pull Request #17846

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/17844.}

[dgrammatiko]

@franz-wohlkoenig can you re open this one?
The PR was wrong
The error is coming from:

[ghost]

reopened as stated above.

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/17844.}

[mbabker]

It is already fixed in staging so either the fix has not yet been merged to 4.0 or it was removed in a merge conflict.

[dgrammatiko]

Actually re installing a fresh copy resolves the issue