Projucer (Xcode): Only code-sign a copy of a plugin when `EXPANDED_CODE_SIGN_IDENTITY` is available

extras/Projucer/Source/ProjectSaving/jucer_ProjectExport_Xcode.h

@@ -2590,14 +2590,16 @@ private:
                                             : "/${FULL_PRODUCT_NAME}";
 
                 const auto codesignScript = ScriptBuilder{}
-                        .ifSet ("CODE_SIGN_ENTITLEMENTS",
-                                R"(entitlementsArg=(--entitlements "${CODE_SIGN_ENTITLEMENTS}"))")
-                        .echo ("Signing Identity: " + doubleQuoted ("${EXPANDED_CODE_SIGN_IDENTITY_NAME}") )
-                        .run ("codesign --verbose=4 --force --sign",
-                              doubleQuoted ("${EXPANDED_CODE_SIGN_IDENTITY}"),
-                              "${entitlementsArg[*]-}",
-                              "${OTHER_CODE_SIGN_FLAGS-}",
-                              doubleQuoted (installPath + objectToSignTail));
+                        .ifSet ("EXPANDED_CODE_SIGN_IDENTITY",
+                                ScriptBuilder{}.ifSet ("CODE_SIGN_ENTITLEMENTS",
+                                                       R"(entitlementsArg=(--entitlements "${CODE_SIGN_ENTITLEMENTS}"))")
+                                               .echo ("Signing Identity: " + doubleQuoted ("${EXPANDED_CODE_SIGN_IDENTITY_NAME}") )
+                                               .run ("codesign --verbose=4 --force --sign",
+                                                   doubleQuoted ("${EXPANDED_CODE_SIGN_IDENTITY}"),
+                                                   "${entitlementsArg[*]-}",
+                                                   "${OTHER_CODE_SIGN_FLAGS-}",
+                                                   doubleQuoted (installPath + objectToSignTail))
+                                               .toString());
 
                 copyPluginStepScript.ifEqual (doubleQuoted ("${CONFIGURATION}"), doubleQuoted (config->getName()),
                                               ScriptBuilder{}.insertScript (copyScript.toString())