feat: Create ErrorHandler to convert errors to Representations

src/storage/conversion/ErrorToQuadConverter.ts

@@ -0,0 +1,37 @@
+import arrayifyStream from 'arrayify-stream';
+import { BasicRepresentation } from '../../ldp/representation/BasicRepresentation';
+import type { Representation } from '../../ldp/representation/Representation';
+import { RepresentationMetadata } from '../../ldp/representation/RepresentationMetadata';
+import { INTERNAL_ERROR, INTERNAL_QUADS } from '../../util/ContentTypes';
+import { InternalServerError } from '../../util/errors/InternalServerError';
+import { DC, SOLID_ERROR } from '../../util/Vocabularies';
+import type { RepresentationConverterArgs } from './RepresentationConverter';
+import { TypedRepresentationConverter } from './TypedRepresentationConverter';
+
+/**
+ * Converts an error object into quads by creating a triple for each of name/message/stack.
+ */
+export class ErrorToQuadConverter extends TypedRepresentationConverter {
+  public constructor() {
+    super(INTERNAL_ERROR, INTERNAL_QUADS);
+  }
+
+  public async handle({ identifier, representation }: RepresentationConverterArgs): Promise<Representation> {
+    const errors = await arrayifyStream(representation.data);
+    if (errors.length !== 1) {
+      throw new InternalServerError('Only single errors are supported.');
+    }
+    const error = errors[0] as Error;
+
+    // A metadata object makes it easier to add triples due to the utility functions
+    const data = new RepresentationMetadata(identifier);
+    data.add(DC.terms.title, error.name);
+    data.add(DC.terms.description, error.message);
+    if (error.stack) {
+      data.add(SOLID_ERROR.terms.stack, error.stack);
+    }
+
+    // Update the content-type to quads
+    return new BasicRepresentation(data.quads(), representation.metadata, INTERNAL_QUADS, false);
+  }
+}