diff --git a/lib/types.js b/lib/types.js
index 5521296c..cba76fd2 100644
--- a/lib/types.js
+++ b/lib/types.js
@@ -202,14 +202,10 @@ class Type {
       if (!UnionType) {
         if (typeof opts.wrapUnions === 'function') {
           // we have a projection function
-          try {
-            projectionFn = opts.wrapUnions(types);
-            UnionType = typeof projectionFn !== 'undefined'
-              ? UnwrappedUnionType
-              : WrappedUnionType;
-          } catch(e) {
-            throw new Error(`Error generating projection function: ${e}`);
-          }
+          projectionFn = opts.wrapUnions(types);
+          UnionType = typeof projectionFn !== 'undefined'
+            ? UnwrappedUnionType
+            : WrappedUnionType;
         } else {
           UnionType = isAmbiguous(types) ? WrappedUnionType : UnwrappedUnionType;
         }
@@ -1319,11 +1315,7 @@ class UnwrappedUnionType extends UnionType {
     super(schema, opts);
 
     if (!_projectionFn && opts && typeof opts.wrapUnions === 'function') {
-      try {
-        _projectionFn = opts.wrapUnions(this.types);
-      } catch(e) {
-        throw new Error(`Error generating projection function: ${e}`);
-      }
+      _projectionFn = opts.wrapUnions(this.types);
     }
     this._getIndex = _projectionFn
       ? generateProjectionIndexer(_projectionFn)