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 a cell holding a static error value — a formula the parser rejected, or an error value entered directly — being reported under the address of whichever cell read it first. Such a cell now reports its own address, and keeps reporting it as rows and columns move around it. After a very long run of structural changes the original position can no longer be reconstructed, and the address is omitted rather than guessed. [#1547](https://github.com/handsontable/hyperformula/issues/1547)
 - A parsing error, an error value typed directly into a cell, and an error literal written into a formula are now attributed to `parser`, `user input`, or `literal` respectively, instead of being silently unattributed or (for a parsing error) reporting no address at all. `#SPILL!` errors now report the cell that failed to spill instead of no address. [#1547](https://github.com/handsontable/hyperformula/issues/1547)
 - Fixed a function or operator being reported as the producer of an error it only read. A reference that cannot be resolved now reports `reference`, and one destroyed by removing rows or columns reports `removed reference`, so `=SUM(A2:A99999999999)` no longer reports `SUM` and `=ABS(A2:A99999999999)` no longer reports an argument index that belongs to nothing. Errors that arise inside an array are attributed to the operation that built the array, so a broadcast gap in `=INDEX(A1:A2+B1:B3, 3, 1)` now reports the `+` operator rather than `INDEX`, and a per-element coercion failure reports the function alongside the argument index. [#1547](https://github.com/handsontable/hyperformula/issues/1547)
+- Reading a formula cell's value before it has been computed now throws a `CellValueNotComputedError` naming the cell's address, instead of a plain `Error` with no way to trace which cell caused it. [#444](https://github.com/handsontable/hyperformula/issues/444)
 - Fixed the `AVERAGEIF` function returning a division-by-zero error when the calculated average was `0`. [#1733](https://github.com/handsontable/hyperformula/pull/1733)
 - Fixed the localized names of `VSTACK` and `HSTACK` in 14 language packs to match Microsoft Excel. [#1748](https://github.com/handsontable/hyperformula/pull/1748)
 - Fixed the MAXPOOL and MEDIANPOOL functions throwing an uncaught `TypeError` instead of returning the `#VALUE!` error when the range dimensions are not a whole multiple of the window size and the stride. [#1718](https://github.com/handsontable/hyperformula/pull/1718)

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)
     }
   }
 

src/errors.ts

@@ -59,6 +59,19 @@ 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. The missing address was the complaint in issue #444.
+ * 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
  */

src/index.ts

@@ -16,6 +16,7 @@ import {
   DenseSparseChooseBasedOnThreshold
 } from './DependencyGraph/AddressMapping/ChooseAddressMappingPolicy'
 import {
+  CellValueNotComputedError,
   ConfigValueTooBigError,
   ConfigValueTooSmallError,
   EvaluationSuspendedError,
@@ -71,6 +72,7 @@ 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
@@ -154,6 +156,7 @@ export {
   ExportedNamedExpressionChange,
   DetailedCellError,
   CellError,
+  CellValueNotComputedError,
   ConfigValueTooBigError,
   ConfigValueTooSmallError,
   EvaluationSuspendedError,