HF-131 (6/7): thrown exceptions name the cell (issue #444)

CHANGELOG.md

@@ -22,6 +22,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fixed the `EDATE` function returning the 28th of February instead of the 29th when the shifted date falls in February of a leap year (e.g. `=EDATE(DATE(2028, 1, 31), 1)` now returns `2028-02-29` instead of `2028-02-28`). [#1781](https://github.com/handsontable/hyperformula/pull/1781)
 - Fixed a cell holding a static error value, such as a rejected formula or a typed-in error, being reported under the address of the cell that read it first instead of its own address. [#1547](https://github.com/handsontable/hyperformula/issues/1547)
 - Fixed `#SPILL!` errors reporting no address; their `address` is now the cell whose array result could not spill. [#1547](https://github.com/handsontable/hyperformula/issues/1547)
+- Fixed reading a formula cell's value before it was computed throwing a plain `Error` that did not say which cell it was; it now throws `CellValueNotComputedError`, which carries the cell's address. [#444](https://github.com/handsontable/hyperformula/issues/444)
 
 ## [3.5.0] - 2026-10-09
 

hyperformula/src/DependencyGraph/FormulaVertex.ts

@@ -9,6 +9,7 @@ import {ArrayValue, ErroredArray, CellArray, NotComputedArray} from '../ArrayVal
 import {CellError, equalSimpleCellAddress, ErrorType, SimpleCellAddress} from '../Cell'
 import {RawCellContent} from '../CellContentParser'
 import {ErrorMessage} from '../error-message'
+import {CellValueNotComputedError} from '../errors'
 import {EmptyValue, getRawValue, InternalScalarValue, InterpreterValue} from '../interpreter/InterpreterValue'
 import {LazilyTransformingAstService} from '../LazilyTransformingAstService'
 import {Maybe} from '../Maybe'
@@ -136,7 +137,7 @@ export class ArrayFormulaVertex extends FormulaVertex {
 
   getCellValue(): InterpreterValue {
     if (this.array instanceof NotComputedArray) {
-      throw Error('Array not computed yet.')
+      throw new CellValueNotComputedError(this.cellAddress)
     }
     return this.array.simpleRangeValue()
   }
@@ -275,7 +276,7 @@ export class ScalarFormulaVertex extends FormulaVertex {
     if (this.cachedCellValue !== undefined) {
       return this.cachedCellValue
     } else {
-      throw Error('Value of the formula cell is not computed.')
+      throw new CellValueNotComputedError(this.cellAddress)
     }
   }
 

hyperformula/src/errors.ts

@@ -61,6 +61,19 @@ export class InvalidAddressError extends Error {
   }
 }
 
+/**
+ * Error thrown when a formula cell's value is read before it has been computed.
+ *
+ * Carries the address as a field, so callers can trace the cell without parsing
+ * it back out of the message.
+ * Thrown by both ScalarFormulaVertex and ArrayFormulaVertex.
+ */
+export class CellValueNotComputedError extends Error {
+  constructor(public readonly address: SimpleCellAddress) {
+    super(`Value of the formula cell (sheet = ${address.sheet}, row = ${address.row}, col = ${address.col}) is not computed.`)
+  }
+}
+
 /**
  * Error thrown when the given arguments are invalid
  */

hyperformula/src/index.ts

@@ -16,6 +16,7 @@ import {
   DenseSparseChooseBasedOnThreshold
 } from './DependencyGraph/AddressMapping/ChooseAddressMappingPolicy'
 import {
+  CellValueNotComputedError,
   ConfigValueTooBigError,
   ConfigValueTooSmallError,
   EvaluationSuspendedError,
@@ -74,6 +75,7 @@ class HyperFormulaNS extends HyperFormula {
   public static DetailedCellError = DetailedCellError
   public static ExportedCellChange = ExportedCellChange
   public static ExportedNamedExpressionChange = ExportedNamedExpressionChange
+  public static CellValueNotComputedError = CellValueNotComputedError
   public static ConfigValueTooBigError = ConfigValueTooBigError
   public static ConfigValueTooSmallError = ConfigValueTooSmallError
   public static EvaluationSuspendedError = EvaluationSuspendedError
@@ -159,6 +161,7 @@ export {
   ExportedNamedExpressionChange,
   DetailedCellError,
   CellError,
+  CellValueNotComputedError,
   ConfigValueTooBigError,
   ConfigValueTooSmallError,
   EvaluationSuspendedError,