mostly implement getting a running process

src/error.rs

@@ -0,0 +1,13 @@
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum Error {
+    #[error("couldn't get handle to process")]
+    HandleError(String),
+    #[error("couldn't create instance of process")]
+    ProcessError(String),
+    #[error("couldn't create snapshot")]
+    SnapshotError(String),
+    #[error("failed to convert integer")]
+    IntegerConversionError(#[from] std::num::TryFromIntError),
+}