comedi: ni_routing: tools: Check when the file could not be opened

- After fopen check NULL before using the file pointer use

Signed-off-by: Ruffalo Lavoisier <RuffaloLavoisier@gmail.com>
Link: https://lore.kernel.org/r/20240906203025.89588-1-RuffaloLavoisier@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: RuffaloLavoisier

drivers/comedi/drivers/ni_routing/tools/convert_c_to_py.c

@@ -140,6 +140,11 @@ int main(void)
 {
 	FILE *fp = fopen("ni_values.py", "w");
 
+	if (fp == NULL) {
+		fprintf(stderr, "Could not open file!");
+		return -1;
+	}
+
 	/* write route register values */
 	fprintf(fp, "ni_route_values = {\n");
 	for (int i = 0; ni_all_route_values[i]; ++i)