Bug #47218 mysqltest ignores "error" command inside if inside loop

This was affected by same problem as append_file etc.
Added Q_ERROR to special handling, and added small test

client/mysqltest.cc

@@ -7708,6 +7708,7 @@ int main(int argc, char **argv)
     if (!ok_to_do)
     {
       if (command->type == Q_SOURCE ||
+          command->type == Q_ERROR ||
           command->type == Q_WRITE_FILE ||
           command->type == Q_APPEND_FILE ||
 	  command->type == Q_PERL)

mysql-test/r/mysqltest.result

@@ -317,6 +317,7 @@ here is the sourced script
 outer=2 ifval=0
 outer=1 ifval=1
 here is the sourced script
+ERROR 42S02: Table 'test.nowhere' doesn't exist
 
 In loop
 here is the sourced script

mysql-test/t/mysqltest.test

@@ -854,6 +854,7 @@ while ($outer)
 }
 
 # Test source in an if in a while which is false on 1st iteration
+# Also test --error in same context
 let $outer= 2; # Number of outer loops
 let $ifval= 0; # false 1st time
 while ($outer)
@@ -862,6 +863,8 @@ while ($outer)
 
   if ($ifval) {
     --source $MYSQLTEST_VARDIR/tmp/sourced.inc
+    --error ER_NO_SUCH_TABLE
+    SELECT * from nowhere;
   }
   dec $outer;
   inc $ifval;