add warning if total parametric volume is less then 1

6 jobs for master in 8 minutes (queued for 4 seconds)
latest
Status Name Job ID Coverage
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passed clang-c++11 #141821
Linux

00:05:51

passed clang-c++14 #141824
Linux

00:07:59

passed gcc-c++11 #141819
Linux

00:02:08

passed gcc-c++14 #141823
Linux

00:02:24

passed macos-c++11 #141826
Apple

00:04:59

passed macos-c++14 #141827
Apple

00:02:58