Remove (almost all) panickers from trie module (#1776)

* memorydb ub patch and other cleanup

* fix denote invocations

* move trie traits into trie module

* replace "denote" with shim

* triedb returns results and no longer panics

* fix warnings

* get ethcore compiling

* warn on trie errors in ethcore

* remove unsafety from node decoder

* restore broken denote behavior for this branch

* fix overlayrecent fallout

* fix triedb tests

* remove unwrap in state

* alter Trie::get to return Result<Option<_>>

* fix refcell error in require

* fix test warnings

* fix json tests

* whitespace

[ci:skip]

* Avoid unneeded match/indentation

* whitespace

* prettify map_or_else

* remove test warning

ethcore/src/client/error.rs

@@ -2,11 +2,15 @@ use trace::Error as TraceError;
 use util::UtilError;
 use std::fmt::{Display, Formatter, Error as FmtError};
 
+use util::trie::TrieError;
+
 /// Client configuration errors.
 #[derive(Debug)]
 pub enum Error {
 	/// TraceDB configuration error.
 	Trace(TraceError),
+	/// TrieDB-related error.
+	Trie(TrieError),
 	/// Database error
 	Database(String),
 	/// Util error
@@ -19,16 +23,29 @@ impl From<TraceError> for Error {
 	}
 }
 
+impl From<TrieError> for Error {
+	fn from(err: TrieError) -> Self {
+		Error::Trie(err)
+	}
+}
+
 impl From<UtilError> for Error {
 	fn from(err: UtilError) -> Self {
 		Error::Util(err)
 	}
 }
 
+impl<E> From<Box<E>> for Error where Error: From<E> {
+	fn from(err: Box<E>) -> Self {
+		Error::from(*err)
+	}
+}
+
 impl Display for Error {
 	fn fmt(&self, f: &mut Formatter) -> Result<(), FmtError> {
 		match *self {
 			Error::Trace(ref err) => write!(f, "{}", err),
+			Error::Trie(ref err) => write!(f, "{}", err),
 			Error::Util(ref err) => write!(f, "{}", err),
 			Error::Database(ref s) => write!(f, "Database error: {}", s),
 		}