syntax errors in mysources.list get ignored

[guillep]

Describe the bug
I have a mysources.list.
I had a syntax error (a comma missing between two templates that I copy pasted).
The launcher ignored it but did not report it.

Buggy:

OrderedCollection [
	PhLTemplateSource {
		#type : #HttpListing,
		#name : 'Pharo 12.0 posta',
		#url : 'https://files.pharo.org/image/90/',
                #filterPattern : 'href="(Pharo-?12(.0)?-SNAPSHOT.build.[^"]*.zip)"'
	}
	PhLTemplateSource {
		#type : #HttpListing,
		#name : 'Pharo 9.0 (stable)',
		#url : 'https://files.pharo.org/image/90/',
                #filterPattern : 'href="(Pharo-?9.0-SNAPSHOT.build.[^"]*.zip)"'
	}
]

Fixed:

OrderedCollection [
	PhLTemplateSource {
		#type : #HttpListing,
		#name : 'Pharo 12.0 posta',
		#url : 'https://files.pharo.org/image/90/',
                #filterPattern : 'href="(Pharo-?12(.0)?-SNAPSHOT.build.[^"]*.zip)"'
	},
	PhLTemplateSource {
		#type : #HttpListing,
		#name : 'Pharo 9.0 (stable)',
		#url : 'https://files.pharo.org/image/90/',
                #filterPattern : 'href="(Pharo-?9.0-SNAPSHOT.build.[^"]*.zip)"'
	}
]

Expected behavior
reporting the error to the user somehow