Axes must be populated before curves for reference entries

Error message

Axes must be populated before curves for reference entries

What it means

Thrown by the radar diagram's computeCurveEntries() when a curve's entries reference axes by name (entry.axis is set) but the shared axes array is still empty. The radar DB needs axes registered first because reference-style entries must be reordered to match the axis order. Without axes there is no canonical ordering to map entries against, so the build aborts rather than emit silently-wrong data.

Source

Thrown at packages/mermaid/src/diagrams/radar/db.ts:82

const setCurves = (curves: Curve[]) => {
  data.curves = curves.map((curve) => {
    return {
      name: curve.name,
      label: curve.label ?? curve.name,
      entries: computeCurveEntries(curve.entries),
    };
  });
};

const computeCurveEntries = (entries: Entry[]): number[] => {
  // If entries have axis reference, we must order them according to the axes
  if (entries[0].axis == undefined) {
    return entries.map((entry) => entry.value);
  }
  const axes = getAxes();
  if (axes.length === 0) {
    throw new Error('Axes must be populated before curves for reference entries');
  }
  return axes.map((axis) => {
    const entry = entries.find((entry) => entry.axis?.$refText === axis.name);
    if (entry === undefined) {
      throw new Error('Missing entry for axis ' + axis.label);
    }
    return entry.value;
  });
};

const setOptions = (options: Option[]) => {
  // Create a map from option names to option objects for quick lookup
  const optionMap = options.reduce(
    (acc, option) => {
      acc[option.name] = option;
      return acc;
    },
    {} as Record<string, Option>

View on GitHub (pinned to d93e9c88c0)

Solutions

Ensure the diagram text declares the `axis` block before the `curve` blocks (reference-mode entries require it).
If calling the db directly, call db.setAxes(...) before db.setCurves(...).
Switch curves to positional entries (drop the `axis <name>` reference) so ordering is taken from the entry list itself.
Re-run db.clear() only once at the start and verify no second clear() runs between setAxes and setCurves.

Example fix

// before (broken order)
db.clear();
db.setCurves(curvesWithAxisRefs); // axes empty -> throws
db.setAxes(axes);

// after
db.clear();
db.setAxes(axes);
db.setCurves(curvesWithAxisRefs);

Defensive patterns

Strategy: validation

Validate before calling

// Before setCurves, ensure axes exist when entries use axis references
const usesRefs = curves.some(c => c.entries.length > 0 && c.entries[0].axis != null);
if (usesRefs && db.getAxes().length === 0) {
  throw new Error('Declare/parse axes before curves that reference them');
}
db.setCurves(curves);

Type guard

const isAxisRefEntry = (e): e is Entry & { axis: { $refText: string } } =>
  e != null && typeof e === 'object' && e.axis != null && typeof e.axis.$refText === 'string';

Try / catch

try {
  db.setCurves(curves);
} catch (e) {
  if (e instanceof Error && /Axes must be populated/.test(e.message)) {
    // ensure axes are set first, then retry once
    db.setAxes(axes);
    db.setCurves(curves);
  } else { throw e; }
}

Prevention

Always set/parse axes before curves in radar diagrams.
When driving the db directly, wrap setAxes+setCurves in a single helper that enforces order.
Use positional entries (no axis ref) if you cannot guarantee axis availability.

When it happens

Trigger: db.setCurves(curves) is invoked before db.setAxes(axes) AND at least one curve's first entry has an `axis` cross-reference ($refText). This normally cannot happen through the parser (it walks axes then curves) but can occur when calling the db API directly, with a hand-built AST, or after a parser/clear() ordering bug that resets data between the two calls.

Common situations: Embedding mermaid and driving the radar db programmatically out of order; partial diagram text where an `axis` block is missing or commented out but curves still use `axis <name>` references; a regression that swaps the populateDb visit order; tests that call setCurves in isolation.

Related errors

AI-assisted analysis of mermaid-js/mermaid@d93e9c88c0 (2026-08-12). Data as JSON: /api/errors/7948898d8b938f0a. Report an issue: GitHub.