Documentation Index
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Error classes thrown during ESM package loading. Import them from @frontmcp/sdk:
import {
EsmPackageLoadError,
EsmVersionResolutionError,
EsmManifestInvalidError,
EsmCacheError,
EsmRegistryAuthError,
EsmInvalidSpecifierError,
} from '@frontmcp/sdk';
Overview
| Error | Base Class | Error Code | HTTP | Description |
|---|
EsmPackageLoadError | InternalMcpError | ESM_PACKAGE_LOAD_ERROR | 500 | Bundle fetch or module evaluation failed |
EsmVersionResolutionError | InternalMcpError | ESM_VERSION_RESOLUTION_ERROR | 500 | npm registry version resolution failed |
EsmManifestInvalidError | PublicMcpError | -32602 (INVALID_PARAMS) | 400 | Package manifest is invalid or missing required fields |
EsmCacheError | InternalMcpError | ESM_CACHE_ERROR | 500 | Cache read/write operation failed |
EsmRegistryAuthError | PublicMcpError | -32001 (UNAUTHORIZED) | 401 | Private registry authentication failed |
EsmInvalidSpecifierError | PublicMcpError | -32602 (INVALID_PARAMS) | 400 | Package specifier string is malformed |
EsmPackageLoadError
Thrown when loading an ESM package fails — including network errors, CDN timeouts, and module evaluation failures.
class EsmPackageLoadError extends InternalMcpError {
readonly packageName: string;
readonly version?: string;
readonly originalError?: Error;
}
| Property | Type | Description |
|---|
packageName | string | Full package name (e.g., @acme/tools) |
version | string? | Resolved version that failed to load |
originalError | Error? | Underlying fetch or evaluation error |
EsmVersionResolutionError
Thrown when the npm registry cannot resolve a version for the given semver range — including network errors, 404s, and no matching version.
class EsmVersionResolutionError extends InternalMcpError {
readonly packageName: string;
readonly range: string;
readonly originalError?: Error;
}
| Property | Type | Description |
|---|
packageName | string | Full package name |
range | string | Semver range that failed to resolve (e.g., ^3.0.0) |
originalError | Error? | Underlying registry error |
EsmManifestInvalidError
Thrown when a package’s default export does not conform to the FrontMcpPackageManifest contract — missing name, version, or invalid primitive arrays.
class EsmManifestInvalidError extends PublicMcpError {
readonly packageName: string;
readonly details?: string;
readonly mcpErrorCode = -32602; // INVALID_PARAMS
}
| Property | Type | Description |
|---|
packageName | string | Full package name |
details | string? | Zod validation error details |
EsmCacheError
Thrown when a cache operation (read, write, cleanup) fails — typically due to file system permission issues or disk space.
class EsmCacheError extends InternalMcpError {
readonly operation: string;
readonly packageName?: string;
readonly originalError?: Error;
}
| Property | Type | Description |
|---|
operation | string | Cache operation that failed (e.g., 'get', 'put', 'cleanup') |
packageName | string? | Package involved in the operation |
originalError | Error? | Underlying I/O error |
EsmRegistryAuthError
Thrown when authentication to a private npm registry fails — invalid token, expired credentials, or wrong registry URL.
class EsmRegistryAuthError extends PublicMcpError {
readonly registryUrl?: string;
readonly details?: string;
readonly mcpErrorCode = -32001; // UNAUTHORIZED
}
| Property | Type | Description |
|---|
registryUrl | string? | Registry URL that rejected authentication |
details | string? | Additional error details |
EsmInvalidSpecifierError
Thrown when a package specifier string is malformed — does not match the expected @scope/name@range or name@range pattern.
class EsmInvalidSpecifierError extends PublicMcpError {
readonly specifier: string;
readonly mcpErrorCode = -32602; // INVALID_PARAMS
}
| Property | Type | Description |
|---|
specifier | string | The invalid specifier string |
