Foundry376/Mailspring · error · Error

Validation failed at ${keyPath}, ${JSON.stringify(value)} mu

Error message

Validation failed at ${keyPath}, ${JSON.stringify(value)} must be an array

What it means

Config schema enforcer for type 'array': Array.isArray failed on the value, so a schema-declared array key received a non-array (usually an object literal or comma-separated string). Each item would otherwise be coerced against schema.items.

Source

Thrown at app/src/config.ts:873

              childSchema
            );
          } catch (error) {
            console.warn(`Error setting item in object: ${error.message}`);
          }
        } else {
          // Just pass through un-schema'd values
          newValue[prop] = propValue;
        }
      }

      return newValue;
    },
  },

  array: {
    coerce(keyPath, value, schema) {
      if (!Array.isArray(value)) {
        throw new Error(
          `Validation failed at ${keyPath}, ${JSON.stringify(value)} must be an array`
        );
      }
      const itemSchema = schema.items;
      if (itemSchema != null) {
        const newValue = [];
        for (const item of value) {
          try {
            newValue.push(this.executeSchemaEnforcers(keyPath, item, itemSchema));
          } catch (error) {
            console.warn(`Error setting item in array: ${error.message}`);
          }
        }
        return newValue;
      } else {
        return value;
      }
    },

View on GitHub (pinned to 648c685d60)

Solutions

1. Write the setting as a JSON array
2. Split delimited strings into arrays before calling config.set

When it happens

Trigger: Thrown at app/src/config.ts:873 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of Foundry376/Mailspring@648c685d60 (2026-09-03). Data as JSON: /api/errors/4d9753ab4c218dfc. Report an issue: GitHub.