Improve error reporting in the asset library and in related types #606

Job	Run time
📊 Static checks / Code style, file formatting, and docs	2m 44s
🤖 Android / Template (target=template_release)	21m 39s
🍏 iOS / Template (target=template_release)	23m 45s
🍎 macOS / Editor (target=editor, tests=yes)	22m 16s
🌐 Web / Template w/ threads (target=template_release, threads=yes)	16m 18s
🏁 Windows / Editor (target=editor, tests=yes)	34m 15s
🍎 macOS / Template (target=template_release)	21m 52s
🌐 Web / Template w/o threads (target=template_release, threads=no)	16m 26s
🐧 Linux / Editor w/ Mono (target=editor)	27m 12s
🏁 Windows / Template (target=template_release)	21m 53s
🐧 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 23s
🐧 Linux / Editor with clang sanitizers (target=editor, tests=yes, dev_build=yes, use_asan=yes, use_ubsan=yes, use_llvm=yes, linker=lld)	24m 47s
🐧 Linux / Editor with ThreadSanitizer (target=editor, tests=yes, dev_build=yes, use_tsan=yes, use_llvm=yes, linker=lld)	22m 41s
🐧 Linux / Template w/ Mono (target=template_release)	17m 6s
🐧 Linux / Minimal template (target=template_release, everything disabled)	12m 33s
🪲 Godot CPP / Build and test Godot CPP	6m 47s
	5h 18m 37s

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