Dear all,

this PR is an obvious followup to PR107000, where invalid
types appeared in array constructors and lead to an ICE
either in a conversion or reduction of a unary or binary
expression.

The present PR shows that several other conversions need to
be protected by a check of the type of the source expression.

Regtested on x86_64-pc-linux-gnu.  OK for mainline?

Thanks,
Harald