fix: prevent error if version not set

Signed-off-by: Paul Horton <[email protected]>

Author: madpah

cyclonedx/output/json.py

@@ -151,7 +151,8 @@ def _recurse_specialise_component(self, bom_json: Dict[Any, Any], base_key: str
                 if not self.component_supports_author() and 'author' in bom_json[base_key][i].keys():
                     del bom_json[base_key][i]['author']
 
-                if self.component_version_optional() and bom_json[base_key][i].get('version', '') == "":
+                if self.component_version_optional() and 'version' in bom_json[base_key][i] \
+                        and bom_json[base_key][i].get('version', '') == "":
                     del bom_json[base_key][i]['version']
 
                 if not self.component_supports_pedigree() and 'pedigree' in bom_json[base_key][i].keys():