chore: make globalSourceMapContext local on the VM such that multiple…

… VMs can run in parallel (#12)

internal/vm/vm.go

@@ -28,11 +28,10 @@ var (
 
 var lineNumberRegex = regexp.MustCompile(` \(*([^ ]+):([0-9]+):([0-9]+)\([0-9]+\)`)
 
-var globalSourceMapCache = map[string]*sourcemap.Consumer{}
-
 // VM is a wrapper around the goja runtime.
 type VM struct {
  *goja.Runtime
+ globalSourceMapCache map[string]*sourcemap.Consumer
 }
 
 // Options represents options for running a script.
@@ -66,7 +65,7 @@ func New() (*VM, error) {
  new(require.Registry).Enable(g)
  console.Enable(g)
 
- return &VM{Runtime: g}, nil
+ return &VM{Runtime: g, globalSourceMapCache: make(map[string]*sourcemap.Consumer)}, nil
 }
 
 // Run runs a script in the VM.
@@ -86,7 +85,7 @@ func (v *VM) Run(name string, src string, opts ...Option) (goja.Value, error) {
  return nil, fmt.Errorf("failed to compile source map for script: %w", err)
  }
 
- globalSourceMapCache[name] = m
+ v.globalSourceMapCache[name] = m
 
  res, err := v.Runtime.RunProgram(p.prog)
  if err == nil {
@@ -99,7 +98,7 @@ func (v *VM) Run(name string, src string, opts ...Option) (goja.Value, error) {
 
  errString := jsErr.String()
 
- fixedStackTrace, _ := utils.ReplaceAllStringSubmatchFunc(lineNumberRegex, errString, remapLineNumbers(name, options.startingLineNumber))
+ fixedStackTrace, _ := utils.ReplaceAllStringSubmatchFunc(lineNumberRegex, errString, v.remapLineNumbers(name, options.startingLineNumber))
 
  return nil, fmt.Errorf("failed to run script %s: %w", fixedStackTrace, ErrRuntime)
 }
@@ -141,7 +140,7 @@ func (v *VM) compile(name string, src string, strict bool) (*program, error) {
  }, nil
 }
 
-func remapLineNumbers(name string, startingLineNumber int) func(match []string) (string, error) {
+func (v *VM) remapLineNumbers(name string, startingLineNumber int) func(match []string) (string, error) {
  return func(match []string) (string, error) {
  const expectedMatches = 4
 
@@ -151,7 +150,7 @@ func remapLineNumbers(name string, startingLineNumber int) func(match []string)
 
  file := match[1]
 
- sm, ok := globalSourceMapCache[file]
+ sm, ok := v.globalSourceMapCache[file]
  if !ok {
  return match[0], nil
  }