Fix package_data for gvpr and empty BOM crash

- Include *.gvpr files in package_data so wv_gvpr.gvpr ships
  in the wheel distribution (reported by web-ui integration agent)
- Guard generate_html_output() against empty BOM list to prevent
  IndexError when YAML has no connectors/cables

setup.py

@@ -29,7 +29,7 @@ setup(
     keywords="cable connector hardware harness wiring wiring-diagram wiring-harness",
     url=APP_URL,
     package_dir={"": "src"},
-    package_data={CMD_NAME: ["templates/*.html"]},
+    package_data={CMD_NAME: ["templates/*.html", "*.gvpr"]},
     packages=find_packages("src"),
     entry_points={
         "console_scripts": [

src/wireviz/wv_output.py

@@ -107,6 +107,7 @@ def generate_html_output(
         )
 
     # generate BOM table
+    if bom:
         # generate BOM header (may be at the top or bottom of the table)
         bom_header_html = "  <tr>\n"
         for item in bom[0]:
@@ -133,6 +134,9 @@ def generate_html_output(
             + bom_header_html
             + "</table>\n"
         )
+    else:
+        bom_html = ""
+        bom_html_reversed = ""
 
     # prepare simple replacements
     replacements = {