Don't allow to sign empty file #1470

Job	Run time
Run CodeQL tests	3m 11s
Build on macOS for macos	2m 2s
Build on Fedora 39	1m 41s
Run Coverity tests	0s
Build on macOS for iphoneos	1m 4s
Build on Fedora 40	1m 32s
Build on macOS for iphonesimulator	1m 12s
Deploy pages	0s
Build on macOS for androidarm	1m 19s
Build on Ubuntu 20.04	2m 32s
Build on macOS for androidarm64	1m 41s
Build on Windows (143, x86)	7m 29s
Build on Ubuntu 22.04	2m 42s
Build on Windows (143, x64)	7m 33s
Build on macOS for androidx86_64	1m 26s
Build on Ubuntu 24.04	3m 28s
Build on Windows (142, x86)	7m 14s
Build on Windows (142, x64)	7m 26s
	53m 32s

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