fix: improve error handling and embedding logic in arrow.ts (#2433)

- Enhanced error messages for schema inference failures to suggest
providing an explicit schema.
- Updated embedding application logic to check for existing destination
columns, allowing for filling embeddings in columns that are all null.
- Added comments for clarity on handling existing columns during
embedding application.

Fixes https://github.com/lancedb/lancedb/issues/2183

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

## Summary by CodeRabbit

- **Bug Fixes**
  - Improved error messages for schema inference to enhance readability.
- Prevented redundant embedding application by skipping columns that
already contain data, avoiding unnecessary errors and computations.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

nodejs/__test__/arrow.test.ts

@@ -592,14 +592,14 @@ describe.each([arrow15, arrow16, arrow17, arrow18])(
         ).rejects.toThrow("column vector was missing");
       });
 
-      it("will provide a nice error if run twice", async function () {
+      it("will skip embedding application if already applied", async function () {
         const records = sampleRecords();
         const table = await convertToTable(records, dummyEmbeddingConfig);
 
         // fromTableToBuffer will try and apply the embeddings again
-        await expect(
-          fromTableToBuffer(table, dummyEmbeddingConfig),
-        ).rejects.toThrow("already existed");
+        // but should skip since the column already has non-null values
+        const result = await fromTableToBuffer(table, dummyEmbeddingConfig);
+        expect(result.byteLength).toBeGreaterThan(0);
       });
     });