Restructure the warning handling for the LaTeXImage.pm module.

This moves the error warnings up to immediately after latex or
pdflatex/xelatex (whichever is the latex2pdf program) runs.  This way
these errors are always warned.

When the `TikZ.pm` module was converted the the `LaTeXImage.pm` module
and restructured for PTX output, it resulted in the case that a `pdf`
file is the end result (such as for hardcopy) not having these warnings
issued.

This is to address issue openwebwork/webwork2#2834.

Author: drgrice1

lib/LaTeXImage.pm

@@ -183,8 +183,17 @@ sub draw {
 			system "cd $working_dir && "
 				. WeBWorK::PG::IO::externalCommand('latex')
 				. " --interaction=nonstopmode image-dvisvgm.tex > latex.stdout 2> /dev/null";
-			move("$working_dir/image-dvisvgm.dvi", "$working_dir/image.dvi");
-			chmod(oct(664), "$working_dir/image.dvi");
+
+			if (-r "$working_dir/image-dvisvgm.dvi") {
+				move("$working_dir/image-dvisvgm.dvi", "$working_dir/image.dvi");
+				chmod(oct(664), "$working_dir/image.dvi");
+			} else {
+				warn 'The dvi file was not created.';
+				if (open(my $err_fh, '<', "$working_dir/latex.stdout")) {
+					while (my $error = <$err_fh>) { warn $error; }
+					close($err_fh);
+				}
+			}
 		} else {
 			warn "Can't open $working_dir/image-dvisvgm.tex for writing.";
 			return '';
@@ -200,47 +209,36 @@ sub draw {
 			system "cd $working_dir && "
 				. WeBWorK::PG::IO::externalCommand('latex2pdf')
 				. " --interaction=nonstopmode image.tex > latex.stdout 2> /dev/null";
-			chmod(oct(664), "$working_dir/image.pdf");
+
+			if (-r "$working_dir/image.pdf") {
+				chmod(oct(664), "$working_dir/image.pdf");
+			} else {
+				warn 'The pdf file was not created.';
+				if (open(my $err_fh, '<', "$working_dir/latex.stdout")) {
+					while (my $error = <$err_fh>) { warn $error; }
+					close($err_fh);
+				}
+			}
 		} else {
 			warn "Can't open $working_dir/image.tex for writing.";
 			return '';
 		}
 	}
 
 	# Make derivatives of the dvi
-	if (($ext eq 'svg' || $ext eq 'tgz') && $svgMethod eq 'dvisvgm') {
-		if (-r "$working_dir/image.dvi") {
-			$self->use_svgMethod($working_dir);
-		} else {
-			warn "The dvi file was not created.";
-			if (open(my $err_fh, "<", "$working_dir/latex.stdout")) {
-				while (my $error = <$err_fh>) {
-					warn $error;
-				}
-				close($err_fh);
-			}
-		}
+	if (($ext eq 'svg' || $ext eq 'tgz') && $svgMethod eq 'dvisvgm' && -r "$working_dir/image.dvi") {
+		$self->use_svgMethod($working_dir);
 	}
 
 	# Make derivatives of the pdf
-	if (($svgMethod ne 'dvisvgm' || $ext ne 'svg') && $ext ne 'pdf') {
-		if (-r "$working_dir/image.pdf") {
-			if (($ext eq 'svg' || $ext eq 'tgz') && $svgMethod ne 'dvisvgm') {
-				$self->use_svgMethod($working_dir);
-			}
-			if ($ext eq 'tgz') {
-				$self->use_convert($working_dir, "png");
-			} elsif ($ext ne 'svg' && $ext ne 'pdf') {
-				$self->use_convert($working_dir, $ext);
-			}
-		} else {
-			warn "The pdf file was not created.";
-			if (open(my $err_fh, "<", "$working_dir/latex.stdout")) {
-				while (my $error = <$err_fh>) {
-					warn $error;
-				}
-				close($err_fh);
-			}
+	if (($svgMethod ne 'dvisvgm' || $ext ne 'svg') && $ext ne 'pdf' && -r "$working_dir/image.pdf") {
+		if (($ext eq 'svg' || $ext eq 'tgz') && $svgMethod ne 'dvisvgm') {
+			$self->use_svgMethod($working_dir);
+		}
+		if ($ext eq 'tgz') {
+			$self->use_convert($working_dir, 'png');
+		} elsif ($ext ne 'svg' && $ext ne 'pdf') {
+			$self->use_convert($working_dir, $ext);
 		}
 	}