ci: use bash and add assertions

.github/workflows/run-examples.yml

@@ -59,16 +59,19 @@ jobs:
           for part in summary-*.md.part; do
             # basename, then everything after "summary-", then everything before ".md.part" (via two rev passes)
             testname="$(basename $part | cut -d- -f2- | rev | cut -d. -f3- | rev)"
+            [[ -n "$testname" ]]
 
             svg="verifyTime-$testname.svg"
-            ls -l $svg
+            ls -l "$svg"
 
             # 1920 hours = 80 days
-            url="$(curl -F"file=@$svg' -Fexpires=1920 http://0x0.st)"
+            url="$(curl -F"file=@$svg" -Fexpires=1920 http://0x0.st)"
+            [[ -n "$url" ]]
 
             pasted="$(echo "$pasted" | sed "s#HISTO${testname}HISTO#$url#g")"
           done
           popd
 
           echo "$pasted" > $GITHUB_STEP_SUMMARY
+        shell: "bash -xe {0}"