Only emit errors once, since we abort on the first one

This is the reason for node-tar's test failure in Node v14

index.js

@@ -50,6 +50,7 @@ class ZlibBase extends Minipass {
       throw new TypeError('invalid options for ZlibBase constructor')
 
     super(opts)
+    this[_sawError] = false
     this[_ended] = false
     this[_opts] = opts
 
@@ -64,7 +65,12 @@ class ZlibBase extends Minipass {
     }
 
     this[_onError] = (err) => {
+      // no sense raising multiple errors, since we abort on the first one.
+      if (this[_sawError])
+        return
+
       this[_sawError] = true
+
       // there is no way to cleanly recover.
       // continuing only obscures problems.
       this.close()
@@ -157,6 +163,8 @@ class ZlibBase extends Minipass {
         // `_processChunk()` adds an 'error' listener. If we don't remove it
         // after each call, these handlers start piling up.
         this[_handle].removeAllListeners('error')
+        // make sure OUR error listener is still attached tho
+        this[_handle].on('error', er => this[_onError](new ZlibError(er)))
       }
     }
 

test/multiple-errors-handled.js

@@ -0,0 +1,54 @@
+const t = require('tap')
+const { Gzip } = require('../')
+
+t.test('only raise once if emitted before writing', t => {
+  t.plan(1)
+
+  const gz = new Gzip()
+
+  // dirty hack to get at the internal handle
+  const kHandle = Object.getOwnPropertySymbols(gz)
+    .filter(sym => sym.toString() === 'Symbol(handle)')[0]
+
+  gz.once('error', er => t.match(er, { message: 'zlib: fart' }))
+  const handle = gz[kHandle]
+  handle.emit('error', new Error('fart'))
+  handle.emit('error', new Error('poop'))
+})
+
+t.test('only raise once if emitted after writing', t => {
+  t.plan(1)
+
+  const gz = new Gzip()
+
+  // dirty hack to get at the internal handle
+  const kHandle = Object.getOwnPropertySymbols(gz)
+    .filter(sym => sym.toString() === 'Symbol(handle)')[0]
+
+  gz.once('error', er => t.match(er, { message: 'zlib: fart' }))
+
+  gz.write('hello, ')
+
+  const handle = gz[kHandle]
+  handle.emit('error', new Error('fart'))
+  handle.emit('error', new Error('poop'))
+})
+
+t.test('only raise once if emitted after writing after emitting', t => {
+  t.plan(1)
+
+  const gz = new Gzip()
+
+  // dirty hack to get at the internal handle
+  const kHandle = Object.getOwnPropertySymbols(gz)
+    .filter(sym => sym.toString() === 'Symbol(handle)')[0]
+
+  gz.once('error', er => t.match(er, { message: 'zlib: fart' }))
+
+  gz.write('hello, ')
+
+  const handle = gz[kHandle]
+  handle.emit('error', new Error('fart'))
+  gz.write(' world')
+  handle.emit('error', new Error('poop'))
+})