why:
Previously, the function 'snapshot_desc.loadSnapshot()' contained the
equivalent of 'eth.decode(@[],SnapshotData)' for some type 'SnapshotData'
which should result in an exception of type 'RlpTypeMismatch'.
Before mid October, this worked for all systems on the Github CI. Since
then, a segfault message in the Github CI can be reproduced on all 64bit
Windows wuns when running 'build/all_tests <id-of-test_txpool>' after the
failed 'make test' directive (the latter one needs to be extended by
'|| true'.) This error cannot be reproduced on my local Win7/64 system
with the same MSYS2 and gcc 11.2.0 compiler.
The fix is, rather than catching an exception, to explicitly check the
first argument of 'eth.decode(@[],SnapshotData)' and act if it is empty.
also:
removed some obsolete {.inline.} annotations.