fix: merge custom options with default options deeply

Previously, the options were not merged deeply, so if anything was set
under e.g. watch, all of the default options under watch also had to be
specified to keep the defaults. This includes the pattern, so if you set
watch.ignore or watch.chokidar, you had to set watch.pattern otherwise
nothing would be watched.

Unfortunately, I had to cast the result to get the correct types here
because mergeDeepRight doesn't set the correct types for array
properties. See DefinitelyTyped/DefinitelyTyped#64424

src/index.ts

@@ -4,7 +4,7 @@ import path from 'path';
 import fs from 'fs-extra';
 import globby from 'globby';
 
-import { concat, mergeRight } from 'ramda';
+import { concat, mergeDeepRight } from 'ramda';
 import type Serverless from 'serverless';
 import type ServerlessPlugin from 'serverless/classes/Plugin';
 import chokidar from 'chokidar';
@@ -296,16 +296,16 @@ class EsbuildServerlessPlugin implements ServerlessPlugin {
     const resolvedOptions = {
       ...(target ? { target } : {}),
     };
-    const withDefaultOptions = mergeRight(DEFAULT_BUILD_OPTIONS);
-    const withResolvedOptions = mergeRight(withDefaultOptions(resolvedOptions));
+    const withDefaultOptions = mergeDeepRight(DEFAULT_BUILD_OPTIONS);
+    const withResolvedOptions = mergeDeepRight(withDefaultOptions(resolvedOptions));
 
     const configPath: string | undefined = this.serverless.service.custom?.esbuild?.config;
 
     const config: ConfigFn | undefined = configPath ? require(path.join(this.serviceDirPath, configPath)) : undefined;
 
     return withResolvedOptions<Configuration>(
       config ? config(this.serverless) : this.serverless.service.custom?.esbuild ?? {}
-    );
+    ) as Configuration;
   }
 
   get functionEntries() {