Correctly handle failures to open a project #614

Job	Run time
📊 Static checks / Code style, file formatting, and docs	2m 52s
🍏 iOS / Template (target=template_release)	3m 4s
🐧 Linux / Editor w/ Mono (target=editor)	9m 51s
🐧 Linux / Editor with doubles and GCC sanitizers (target=editor, tests=yes, dev_build=yes, scu_build=yes, precision=double, use_asan=yes, use_ubsan=yes, linker=gold)	26m 55s
🐧 Linux / Editor with clang sanitizers (target=editor, tests=yes, dev_build=yes, use_asan=yes, use_ubsan=yes, use_llvm=yes, linker=lld)	27m 50s
🍎 macOS / Editor (target=editor, tests=yes)	37m 45s
🤖 Android / Template (target=template_release)	3m 53s
🏁 Windows / Editor (target=editor, tests=yes)	37m 21s
🍎 macOS / Template (target=template_release)	2m 59s
🐧 Linux / Editor with ThreadSanitizer (target=editor, tests=yes, dev_build=yes, use_tsan=yes, use_llvm=yes, linker=lld)	24m 30s
🐧 Linux / Template w/ Mono (target=template_release)	4m 16s
🐧 Linux / Minimal template (target=template_release, everything disabled)	49s
🌐 Web / Template w/ threads (target=template_release, threads=yes)	4m 4s
🏁 Windows / Template (target=template_release)	26m 5s
🌐 Web / Template w/o threads (target=template_release, threads=no)	18m 45s
🪲 Godot CPP / Build and test Godot CPP	6m 44s
	3h 57m 43s

Provide feedback