Fix nil pointer dereference in import statement completions

[Copilot]

The language server panics when requesting completions after typing keywords in import statements (e.g., import super, import this).

Root Cause

ImportDeclaration.ImportClause is optional in the AST, but getImportStatementCompletionInfo unconditionally calls IsTypeOnly() on it:

// Before - crashes when ImportClause is nil
result.isTopLevelTypeOnly = candidate.ImportClause().IsTypeOnly()

This occurs when parsing incomplete import statements like import <keyword>, where no ImportClause is created.

Changes

• Add nil check before accessing ImportClause, matching the pattern used elsewhere in the file (line 5139)
• Add regression test covering import super and import this scenarios

// After - safely handles nil ImportClause
if importClause := candidate.ImportClause(); importClause != nil {
    result.isTopLevelTypeOnly = importClause.IsTypeOnly()
}

Original prompt

---

This section details on the original issue you should resolve

<issue_title>textDocument/completion runtime error: invalid memory address or nil pointer dereference</issue_title>
<issue_description>## Stack trace

2026-01-24 10:30:58.816 [error] panic handling request textDocument/completion: runtime error: invalid memory address or nil pointer dereference
goroutine 40293 [running]:
runtime/debug.Stack()
	runtime/debug/stack.go:26 +0x64
github.com/microsoft/typescript-go/internal/lsp.(*Server).recover(0x40001b6e08, {0x861a0?, 0x4005051500?}, 0x400d5bc660)
	github.com/microsoft/typescript-go/internal/lsp/server.go:777 +0x40
panic({0x77e1e0?, 0x12b5a00?})
	runtime/panic.go:783 +0x120
github.com/microsoft/typescript-go/internal/ast.(*Node).IsTypeOnly(...)
	github.com/microsoft/typescript-go/internal/ast/ast.go:923
github.com/microsoft/typescript-go/internal/ls.(*LanguageService).getImportStatementCompletionInfo(0x401e94f280, 0x40161cb740, 0x4003e343c0?)
	github.com/microsoft/typescript-go/internal/ls/completions.go:5110 +0x408
github.com/microsoft/typescript-go/internal/ls.(*LanguageService).getCompletionData(0x401e94f280, {0xc422a8, 0x4013391860}, 0x401ab6e608, 0x4013387508, 0xa7, 0x40076b9a00)
	github.com/microsoft/typescript-go/internal/ls/completions.go:528 +0x25c
github.com/microsoft/typescript-go/internal/ls.(*LanguageService).getCompletionsAtPosition(0x401e94f280, {0xc422a8, 0x4013391860}, 0x4013387508, 0xa7, 0x0)
	github.com/microsoft/typescript-go/internal/ls/completions.go:347 +0x284
github.com/microsoft/typescript-go/internal/ls.(*LanguageService).ProvideCompletion(0x401e94f280, {0xc422a8, 0x40133917a0}, {0x40000ce080?, 0x40133917a0?}, {0xce080?, 0x40?}, 0x4011d69370)
	github.com/microsoft/typescript-go/internal/ls/completions.go:47 +0xd0
github.com/microsoft/typescript-go/internal/lsp.(*Server).handleCompletion(0x4021c0a7e0?, {0xc422a8?, 0x40133917a0?}, 0x40000ce080?, 0xffff9c527f30?)
	github.com/microsoft/typescript-go/internal/lsp/server.go:1095 +0x3c
github.com/microsoft/typescript-go/internal/lsp.init.func1.registerLanguageServiceWithAutoImportsRequestHandler[...].28({0xc422a8, 0x40133917a0}, 0x400d5bc660)
	github.com/microsoft/typescript-go/internal/lsp/server.go:682 +0xf4
github.com/microsoft/typescript-go/internal/lsp.(*Server).handleRequestOrNotification(0x40001b6e08, {0xc422e0?, 0x40151938b0?}, 0x400d5bc660)
	github.com/microsoft/typescript-go/internal/lsp/server.go:531 +0x170
github.com/microsoft/typescript-go/internal/lsp.(*Server).dispatchLoop.func1()
	github.com/microsoft/typescript-go/internal/lsp/server.go:414 +0x34
created by github.com/microsoft/typescript-go/internal/lsp.(*Server).dispatchLoop in goroutine 6
	github.com/microsoft/typescript-go/internal/lsp/server.go:438 +0x7d8

2026-01-24 10:30:58.816 [error] Request textDocument/completion failed.
  Message: InternalError: panic handling request textDocument/completion: runtime error: invalid memory address or nil pointer dereference
  Code: -32603

Steps to reproduce

I was typing right here at the top. Seems pretty consistent to reproduce unlike other crashes I've experienced. Crashes right when I type the r in super

import type { CacheInvalidationOptions, CacheProvider, CacheEntry } from '../types'
import { Redis } from 'ioredis'
import { getTotalTtl } from '../utils'
import super // ⚠️ I was typing here

export class RedisCacheProvider implements CacheProvider {
  private readonly redis: Redis

  constructor(options: RedisCacheProviderOptions) {
    this.redis = new Redis(options.url)
  }

  async get(key: string) {
    const entryJson = await this.redis.get(formatQueryKey(key))

    if (!entryJson) {
      return undefined
    }

    return JSON.parse(entryJson) as CacheEntry
  }

  async set(key: string, entry: CacheEntry) {
    const multi = this.redis.multi()
    const formattedKey = formatQueryKey(key)

    multi.set(formattedKey, JSON.stringify(entry))

    const totalTtl = getTotalTtl(entry)

    if (totalTtl > 0) {
      multi.expire(formattedKey, totalTtl)
    }

    if (entry.options.tags) {
      for (const tag of entry.options.tags) {
        const formattedTagKey = formatTagKey(tag)

        multi.sadd(formattedTagKey, formattedKey)

        if (totalTtl > 0) {
          multi.expire(formattedTagKey, totalTtl, 'GT')
          multi.expire(formattedTagKey, totalTtl, 'NX')
        }
      }
    }

    await multi.exec()
  }

  async invalidate(options: CacheInvalidationOptions) {
    if (options.tags && options.tags.length > 0) {
      await Promise.all(
        options.tags.map(tag => {
          return new Promise((resolve, reject) => {
            const stream = this.redis.sscanStream(formatTagKey(tag), {
              count: 100,
            })

            stream.on('data', async (keys: string[]) => {
              if (keys.length > 1) {
                await this.redis.del(...keys)
              }
            })

            stream.on('error', reject)
            stre...

</details>



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- Fixes microsoft/typescript-go#2580

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