diff --git a/src/clientSideScene/sceneEntities.ts b/src/clientSideScene/sceneEntities.ts
index bf29bae2b5..c9f1f35192 100644
--- a/src/clientSideScene/sceneEntities.ts
+++ b/src/clientSideScene/sceneEntities.ts
@@ -92,7 +92,7 @@ import {
   updateRectangleSketch,
 } from 'lib/rectangleTool'
 import { getThemeColorForThreeJs, Themes } from 'lib/theme'
-import { err, reportRejection, trap } from 'lib/trap'
+import { err, Reason, reportRejection, trap } from 'lib/trap'
 import { CSS2DObject } from 'three/examples/jsm/renderers/CSS2DRenderer'
 import { Point3d } from 'wasm-lib/kcl/bindings/Point3d'
 import { SegmentInputs } from 'lang/std/stdTypes'
@@ -1517,7 +1517,7 @@ export class SceneEntities {
         maybeSketch,
         variableDeclarationName
       )
-      if (typeof sk !== 'string') {
+      if (!(sk instanceof Reason)) {
         sketch = sk
       } else if ((maybeSketch as Solid).sketch) {
         sketch = (maybeSketch as Solid).sketch
diff --git a/src/components/ModelingSidebar/ModelingPanes/MemoryPane.tsx b/src/components/ModelingSidebar/ModelingPanes/MemoryPane.tsx
index d3597b20c5..9e7ba83a83 100644
--- a/src/components/ModelingSidebar/ModelingPanes/MemoryPane.tsx
+++ b/src/components/ModelingSidebar/ModelingPanes/MemoryPane.tsx
@@ -10,7 +10,7 @@ import {
 import { useKclContext } from 'lang/KclProvider'
 import { useResolvedTheme } from 'hooks/useResolvedTheme'
 import { ActionButton } from 'components/ActionButton'
-import { trap } from 'lib/trap'
+import { Reason, trap } from 'lib/trap'
 import Tooltip from 'components/Tooltip'
 import { useModelingContext } from 'hooks/useModelingContext'
 
@@ -98,7 +98,7 @@ export const processMemory = (programMemory: ProgramMemory) => {
         processedMemory[key] = val.value.map(({ ...rest }: ExtrudeSurface) => {
           return rest
         })
-      } else if (typeof sk !== 'string') {
+      } else if (!(sk instanceof Reason)) {
         processedMemory[key] = sk.paths.map(({ __geoMeta, ...rest }: Path) => {
           return rest
         })
diff --git a/src/lang/queryAst.ts b/src/lang/queryAst.ts
index ca797a4e77..61f8f892cb 100644
--- a/src/lang/queryAst.ts
+++ b/src/lang/queryAst.ts
@@ -28,7 +28,7 @@ import {
   getConstraintLevelFromSourceRange,
   getConstraintType,
 } from './std/sketchcombos'
-import { err } from 'lib/trap'
+import { err, Reason } from 'lib/trap'
 import { ImportStatement } from 'wasm-lib/kcl/bindings/ImportStatement'
 import { Node } from 'wasm-lib/kcl/bindings/Node'
 
@@ -792,7 +792,7 @@ export function hasExtrudeSketch({
   const varValue = programMemory?.get(varName)
   return (
     varValue?.type === 'Solid' ||
-    typeof sketchFromKclValueOptional(varValue, varName) !== 'string'
+    !(sketchFromKclValueOptional(varValue, varName) instanceof Reason)
   )
 }
 
diff --git a/src/lang/wasm.ts b/src/lang/wasm.ts
index 28ab05107a..5c78a76106 100644
--- a/src/lang/wasm.ts
+++ b/src/lang/wasm.ts
@@ -32,7 +32,7 @@ import { CoreDumpManager } from 'lib/coredump'
 import openWindow from 'lib/openWindow'
 import { DefaultPlanes } from 'wasm-lib/kcl/bindings/DefaultPlanes'
 import { TEST } from 'env'
-import { err } from 'lib/trap'
+import { err, Reason } from 'lib/trap'
 import { Configuration } from 'wasm-lib/kcl/bindings/Configuration'
 import { DeepPartial } from 'lib/types'
 import { ProjectConfiguration } from 'wasm-lib/kcl/bindings/ProjectConfiguration'
@@ -360,7 +360,7 @@ export class ProgramMemory {
 export function sketchFromKclValueOptional(
   obj: any,
   varName: string | null
-): Sketch | string {
+): Sketch | Reason {
   if (obj?.value?.type === 'Sketch') return obj.value
   if (obj?.value?.type === 'Solid') return obj.value.sketch
   if (obj?.type === 'Solid') return obj.sketch
@@ -369,9 +369,11 @@ export function sketchFromKclValueOptional(
   }
   const actualType = obj?.value?.type ?? obj?.type
   if (actualType) {
-    return `Expected ${varName} to be a sketch or solid, but it was ${actualType} instead.`
+    return new Reason(
+      `Expected ${varName} to be a sketch or solid, but it was ${actualType} instead.`
+    )
   } else {
-    return `Expected ${varName} to be a sketch, but it wasn't.`
+    return new Reason(`Expected ${varName} to be a sketch, but it wasn't.`)
   }
 }
 
@@ -381,8 +383,8 @@ export function sketchFromKclValue(
   varName: string | null
 ): Sketch | Error {
   const result = sketchFromKclValueOptional(obj, varName)
-  if (typeof result === 'string') {
-    return new Error(result)
+  if (result instanceof Reason) {
+    return result.toError()
   }
   return result
 }
diff --git a/src/lib/trap.ts b/src/lib/trap.ts
index 686571d79b..ab4551a42a 100644
--- a/src/lib/trap.ts
+++ b/src/lib/trap.ts
@@ -2,6 +2,23 @@ import toast from 'react-hot-toast'
 
 type ExcludeErr<T> = Exclude<T, Error>
 
+/**
+ * Similar to Error, but more lightweight, without the stack trace.  It can also
+ * be used to represent a reason for not being able to provide an alternative,
+ * which isn't necessarily an error.
+ */
+export class Reason {
+  message: string
+
+  constructor(message: string) {
+    this.message = message
+  }
+
+  toError() {
+    return new Error(this.message)
+  }
+}
+
 /**
  * This is intentionally *not* exported due to misuse.  We'd like to add a lint.
  */