### Bigger Errors - Crashes { #bigger-errors-crashes }

Nevertheless, there might be cases where we write some code that **crashes the entire application** making Uvicorn and Python crash. 💥

    lookup for the local hostname, but we really just wanted the `Host` header.
 *  Fix: Don't crash with a `InaccessibleObjectException` when detecting the platform trust manager
    on Java 17+.
 *  Fix: Don't crash if a cookie's value is a lone double quote character.
 *  Fix: Don't crash when canceling an event source created by `EventSources.processResponse()`.

  }

  // Verify that StackOverflowError in a long chain of SetFuture doesn't cause the entire toString
  // call to fail
  @J2ktIncompatible
  @GwtIncompatible
  @AndroidIncompatible // b/391667564: crashes from stack overflows
  public void testSetFutureToString_stackOverflow() {
    SettableFuture<String> orig = SettableFuture.create();
    SettableFuture<String> prev = orig;
    for (int i = 0; i < 100000; i++) {

  }

  // Verify that StackOverflowError in a long chain of SetFuture doesn't cause the entire toString
  // call to fail
  @J2ktIncompatible
  @GwtIncompatible
  @AndroidIncompatible // b/391667564: crashes from stack overflows
  public void testSetFutureToString_stackOverflow() {
    SettableFuture<String> orig = SettableFuture.create();
    SettableFuture<String> prev = orig;
    for (int i = 0; i < 100000; i++) {

    // be deleted when those files are closed.
    if (!civilizedFileSystem) {
      if (entry.lockingSourceCount > 0) {
        // Mark this entry as 'DIRTY' so that if the process crashes this entry won't be used.
        journalWriter?.let {
          it.writeUtf8(DIRTY)
          it.writeByte(' '.code)
          it.writeUtf8(entry.key)
          it.writeByte('\n'.code)
          it.flush()

*   Fixes multiple crashes due to overflow and `CHECK`-fail in ops with large
    tensor shapes
    ([CVE-2021-41197](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-41197))
*   Fixes a crash in `max_pool3d` when size argument is 0 or negative
    ([CVE-2021-41196](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-41196))
*   Fixes a crash in `tf.math.segment_*` operations

# Classes as Dependencies { #classes-as-dependencies }

Before diving deeper into the **Dependency Injection** system, let's upgrade the previous example.

## A `dict` from the previous example { #a-dict-from-the-previous-example }

In the previous example, we were returning a `dict` from our dependency ("dependable"):

{* ../../docs_src/dependencies/tutorial001_an_py310.py hl[9] *}

    }

    /**
     * Test the getErrorString method with various error classes and codes to ensure all branches are covered.
     */
    @ParameterizedTest
    @MethodSource("provideErrorClassAndCodeForGetErrorString")
    @DisplayName("getErrorString should return correct messages for all defined error classes and codes")
    void testGetErrorString(int errorClass, int errorCode, String expectedMessage) {

        if: failure() || cancelled()
        with:
          name: ${{ github.run_number }}-integration-test-artifact-${{ runner.os }}-${{ matrix.java }}

But remember that when you import `Query`, `Path`, `Header`, and others from `fastapi`, those are actually functions that return special classes.

///

/// info

To declare headers, you need to use `Header`, because otherwise the parameters would be interpreted as query parameters.

///

## Automatic conversion { #automatic-conversion }