JMESPath parser: catch exceptions to show which feed has an error

The MR rethrows the exception like this:

Syntax error for feed MyFeed in file private://yoyo/parsed/my-set.json: Syntax error at character 0 ^ Unexpected "eof" token (nud_eof). Expected one of the following tokens: "identifier", "quoted_identifier", "current", "literal", "expref", "not", "lparen", "lbrace", "flatten", "filter", "star", "lbracket"

This is very helpful in CI environments where you are importing a bunch of feeds, because now you can immediately tell which import caused the problem just by looking at the error.

It would be useful to see when this exactly fails. It looks like it doesn't occur when there is a syntax error in the JSON, because then there's a RuntimeException. (This error message now includes the JSON string, which was added in ✨ Add a feature to display JSON errors Fixed ).

This needs test coverage. The test should check if the feed name and the file path are getting displayed. Perhaps it needs to be a Kernel test if it turns out to be hard to fit it in an Unit test.