printer: check if specs exist before accessing them in genDecl printer
Checks that specs exist before attempting to access the first element in genDecl printer.
Change-Id: I3619bcabf6fec64c88b7a10cdb7be355e9e40559
GitHub-Last-Rev:
54cf699c969cb88cfd269f847a2bb4f25916be94
GitHub-Pull-Request: golang/go#30823
Reviewed-on: https://go-review.googlesource.com/c/go/+/167390
Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>