fix(gatsby): don't break builds when using features unsupported by adapter

packages/gatsby-cli/src/structured-errors/error-map.ts

@@ -926,6 +926,9 @@ const errors: Record<string, IErrorMapEntry> = {
     type: Type.ADAPTER,
     category: ErrorCategory.SYSTEM,
   },
+  // Currently not used, as the error was turned into warning
+  // Might be used in next major version of gatsby, but we still have to keep it
+  // because older gatsby versions might try to use this error ID
   "12201": {
     text: (context): string =>
       `Adapter "${

packages/gatsby/src/utils/adapter/manager.ts

@@ -73,9 +73,7 @@ async function setAdapter({
       store.getState().program.prefixPaths &&
       store.getState().config.pathPrefix
     ) {
-      incompatibleFeatures.push(
-        `pathPrefix is not supported. Please remove the pathPrefix option from your gatsby-config, don't use "--prefix-paths" CLI toggle or PREFIX_PATHS environment variable.`
-      )
+      incompatibleFeatures.push(`pathPrefix is not supported.`)
     }
 
     // trailingSlash support
@@ -98,13 +96,13 @@ async function setAdapter({
     }
 
     if (incompatibleFeatures.length > 0) {
-      reporter.panic({
-        id: `12201`,
-        context: {
-          adapterName: instance.name,
-          incompatibleFeatures,
-        },
-      })
+      reporter.warn(
+        `Adapter "${
+          instance.name
+        }" is not compatible with following settings:\n${incompatibleFeatures
+          .map(line => ` - ${line}`)
+          .join(`\n`)}`
+      )
     }
 
     if (configFromAdapter.pluginsToDisable.length > 0) {